1885.] G. M. Giles— O/i the Prothallus o/Padina pavonia. 73 



From the appearances presented in section, as well as from teazed 

 preparations, it is evident that, in each case, we have to do with specia- 

 lized tubular masses of cells embedded in a tissue consisting of cells 

 differing somewhat from the " nutritive cells" that form the body of the 

 central mass, and more liberally permeated with bands of the adeniform 

 tissue. 



Let us first take the smaller kind. Through the greater part of 

 their length they are simple tubes consisting of a sort of basement mem- 

 brane, lined with small flattened granular cells, containing but little 

 chlorophyll, about 5 m. in diameter. They appeared to end caecally, 

 and their lower part was filled with masses of cells having the following 

 characteristics. Each little mass (Fig. 5) consists of a mother-cell of 

 oval form about 40 m. long by 25 m. cross measurement, containing three 

 daughter-cells. In the interior of these latter a curious change was in 

 the process, resulting in the formation of a number of small spherules of 

 a brilliant carmine colour about 2 or 3 m. in diameter, which in their 

 turn break up into a number of minute rods of the same bright colour 

 about 2 or 3 m. long by 1 m. or less in diameter. From the general 

 characteristics of this organ, there can be little doubt that these rods 

 come under the category of antherozoids, and that the organs themselves 

 are antheridia. 



The larger tubes are usually found in close proximity to the smaller 

 kind, being commonly enclosed in the same sheath of small-celled tissue. 

 Their cellular lining is usually much thicker than that of the antheridial 

 tubes consisting usually of at least two layers of larger cells. The 

 greater part of their length is usually filled up with mother and daughter 

 cells, differing from those of the antheridial tubes in containing no 

 coloured spherules or rods, and in the more abundantly granular 

 character of their contents The portion of the section shewn in Fig. 6. 

 appears to shew their mode of origin : here a cell of the lining has 

 grown out into the lumen of the tube, and has produced a string of cells 

 which has curled round on itself for a turn and a half in a circinate 

 manner ; the oldest cell in the middle of the helix is dividing into 

 daughter-cells ; some of these, however, were elsewhere met with 

 of considerably greater size than those shewn here, which are obviously 

 in the earliest stage of their development. 



So far as could be made out, these tubes had no communication 

 with the exterior, being rather of the nature of closed elongated sacs. 

 Many were met with in a broken-down condition ; and fertilization no 

 doubt takes place by this retrogressive process setting free the ripe con- 

 tents of the tubes, which, being thus liberated in close proximity, and 

 suspended in the grumous matter resulting from the degeneration of the 



